Microchip Technology AT24CS32-XHM-T

Overview

AT24CS32-XHM-T from Microchip Technology is a 32-Kbit I²C-compatible serial EEPROM with factory-programmed 128-bit unique serial number, organized as 4,096 × 8 bits, operating from 1.7V to 5.5V across -40°C to +85°C industrial temperature range. It supports 1 MHz Fast Mode Plus (2.5–5.5V), includes hardware write-protection via WP pin, and delivers ultra-low standby current (6 µA max) for battery-powered asset tracking and secure device identification.

For engineers reviewing the AT24CS32-XHM-T datasheet, AT24CS32-XHM-T pinout, AT24CS32-XHM-T application, or AT24CS32-XHM-T equivalent, this page provides verified pin functions, real-world timing behavior (tWR ≤ 5 ms), memory organization (128 pages × 32 bytes), serial number access protocol (device address 0xB0–0xBF), and validated alternatives for secure serialization in IoT edge nodes and industrial controllers.

Technical Context

The AT24CS32-XHM-T implements a two-wire I²C slave interface with Schmitt-triggered SCL/SDA inputs and integrated noise filtering, supporting Standard (100 kHz), Fast (400 kHz), and Fast Mode Plus (1 MHz) clock rates depending on VCC level. Its internal architecture includes a dedicated 128-bit read-only serial number block-physically isolated from user memory-with no address overlap or endurance impact.

Write protection is enforced via dedicated WP pin: hardwired to VCC disables all writes to the full 32-Kbit array, while floating or GND-connected enables standard byte/page writes. The device uses internal high-voltage generation for EEPROM programming and features automatic power-on reset (VPOR = 1.5 V) with tPUP = 100 µs minimum delay before command acceptance.

Key Specifications

Pinout & Package

AT24CS32-XHM-T is supplied in an 8-lead SOIC package (package code XHM). Pin functions are electrically identical across SOIC, TSSOP, UDFN, and SOT23 variants per Microchip DS20006341A.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM with unique ID applications.

Compared with AT24CS32-XHM-T, AT24CS64-XHM-T offers scalable memory without altering board design or firmware I²C drivers, whereas M95M02-DRMN6TP/K trades built-in security for raw speed and capacity - requiring separate ID provisioning infrastructure.

Availability

AT24CS32-XHM-T is available at Aetrix Electronics and suitable for industrial sensor calibration, secure device authentication, and automotive module identification requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.

Supply support for AT24CS32-XHM-T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a global semiconductor company specializing in microcontrollers, analog devices, and memory solutions, with ISO 9001-certified manufacturing and broad industrial qualification.

The AT24CS32-XHM-T belongs to Microchip's CS Series Serial EEPROM family, designed specifically to eliminate factory serialization overhead while maintaining robust I²C compatibility and extended data retention for mission-critical embedded systems.

FAQ

What is the factory-programmed serial number format and access method for AT24CS32-XHM-T?

The AT24CS32-XHM-T contains a permanent 128-bit (16-byte) serial number programmed during wafer fabrication and locked against overwrite. It resides in a dedicated memory block addressed using I²C device address 0xB0–0xBF (instead of standard 0x50–0x57), requiring a separate 2-byte address pointer. This serial number is guaranteed unique across all Microchip CS Series EEPROMs, including AT24CS01 through AT24CS128, and does not consume any of the 32-Kbit user memory space.

Does AT24CS32-XHM-T support 1 MHz I²C operation at 1.8 V?

No. AT24CS32-XHM-T supports 1 MHz Fast Mode Plus only at VCC = 2.5 V to 5.5 V. At 1.8 V, maximum supported speed is 400 kHz Fast Mode. This limitation is specified in DS20006341A Section 4.4 AC Characteristics: fSCL = 1000 kHz is conditional on VCC ≥ 2.5 V. Operating at 1.8 V with 1 MHz clock violates timing parameters (e.g., tLOW min = 500 ns) and risks communication failure.

How does the WP pin function on AT24CS32-XHM-T, and what happens if left unconnected?

When WP is tied to VCC, AT24CS32-XHM-T inhibits all write operations to its entire 32-Kbit memory array. When connected to GND, normal byte/page writes are enabled. If left floating, the internal weak pull-down biases WP to GND, enabling writes - but Microchip explicitly warns this is unreliable due to capacitive coupling; designs must hardwire WP to a defined state (VCC or GND) using ≤10 kΩ resistors for production robustness.

What is the maximum write cycle time for AT24CS32-XHM-T, and how does it affect firmware update design?

The AT24CS32-XHM-T guarantees a maximum self-timed write cycle time of 5 ms (tWR), applicable to both byte and 32-byte page writes. During this period, the device does not acknowledge I²C START conditions. Firmware must implement acknowledge polling (repeated START + device address until ACK received) or fixed 5 ms delays between write commands. This timing directly impacts over-the-air update latency and must be budgeted in bootloader timeout calculations.

Is AT24CS32-XHM-T compatible with standard 32-Kbit I²C EEPROM software drivers?

Yes - AT24CS32-XHM-T is software-compatible with legacy AT24C32 drivers for basic read/write operations, as it uses identical memory organization (4,096 × 8), addressing scheme, and I²C protocol. However, drivers accessing the 128-bit serial number must use device address 0xB0–0xBF instead of 0x50–0x57, and must not assume WP pin behavior matches older AT24Cxx parts (AT24CS32-XHM-T's WP has stronger internal pull-down).